Berlin 2015 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 39: Posters II (Topological insulators; Graphene; Spintronics and spin physics; Quantum information science)
HL 39.14: Poster
Tuesday, March 17, 2015, 14:00–20:00, Poster F
Bend Resistance in Nanoscale Epitaxial Bilayer Graphene Cross Junctions — •Epaminondas Karaissaridis1, Claudia Bock1, Florian Speck2, Thomas Seyller2, and Ulrich Kunze1 — 1Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum — 2Technische Physik, Technische Universität Chemnitz
We investigated inertial-ballistic transport in nanoscale orthogonal cross junctions prepared on epitaxial bilayer graphene on SiC(0001) [1]. The average film thickness of 1.8 layers was determined by XPS measurements. Hall bars were used to characterize the graphene bilayer by Hall measurements in a temperature range of 1.5 K ≤ T ≤ 300 K. At low temperatures (T ≤ 50 K) a mobility of µ ≈ 1400 cm2/(Vs) and an electron density of n ≈ 4 · 1012 cm−2 were determined. 50 nm wide cross junctions were studied in bend resistance geometry by DC measurements. We obtained a negative bend resistance of R = −525 Ω at T = 4.2 K indicating ballistic transport. The measured bend resistance is three times higher than the value obtained from similar devices on monolayer graphene [2, 3]. Even at T = 100 K, we determined a negative bend resistance of R = −110 Ω which promises ballistic transport well above 100 K. We suppose that the enhanced bend resistance in bilayer graphene is a consequence of its bandgap. This results in a depletion region that reduces scattering at the edges which is an important scattering mechanism in narrow graphene channels.
[1] T. Ohta et al., Science 313, 951 (2006).
[2] S. Weingart et al., Appl. Phys. Lett. 95, 262101 (2009).
[3] C. Bock et al., Nanotechnology 23, 395203 (2012).